Customs officers at Ho Chi Minh City's Tan Son Nhat Airport seized more than five kilograms of rhino horn allegedly smuggled in by a passenger Monday, two weeks after Vietnam and South Africa agreed to an action plan to curb rhino poaching.

D.V.S, a 31-year-old man, was caught with six pieces of horns in his suitcase after arriving on a Vietnam Airlines flight from Europe.

The horns, wrapped in a wool scarf, were cleverly hidden, the officers said.

He claimed to have brought the horns for making medicines to treat ailments and that he did not know their value.

S. and the horns were handed over to the police for investigation.

Seizures of rhino horns at airports occur frequently in Vietnam, with most claiming it is meant for medicinal purposes.

On May 6 South African Deputy Water and Environmental Affairs Minister Rejoice Mabudafhasi and Vietnamese Deputy Minister of Agriculture and Rural Development Ha Cong Tuan signed an "action plan" aimed primarily at addressing rhino poaching in South Africa.

Among others, the two countries agreed to exchange the names of registered hunters in a bid to stop poachers who obtain hunting permits under false pretenses.

Authorities are targeting these hunters who take advantage of laws allowing them to export rhino horns as a hunting trophy to trade it illegally, mostly on the Asian black market, AFP reported.

South Africa, home to more than 20,000 rhinos, or about 90 percent of all rhinos in Africa, lost 668 of them to poachers last year. Over 270 of the magnificent beasts have been killed this year for their horns.

Records of rhino hunting permits show Asians are the largest group of applicants, AFP said.

Thirteen out of 41 permits granted in KwaZulu-Natal Province between 2009 and 2011 were to Vietnamese, it added.

International conservation groups have also identified Vietnam as one of the world's largest consumers of rhino horns.